1. Field of the Invention
The invention relates to a balancing device for a washing machine, and more particularly, the invention relates to a speed dependant response control balancing device to prevent vibration of a rotating basket in a washing machine.
2. Brief Description of the Related Art
Vertical axis washing machines often go out of balance at the start of rotation of the basket and at high rotational speeds due to an uneven distribution of the load in the washing machine basket. The effect of the imbalance at high rotational speeds causing undesirable vibration may cause damage to the motor, cause the basket to bump violently against the outer shell of the washing machine, and even cause the washing machine to "walk" across the floor.
To address both the start up imbalance and the associated high speed vibrations, manufacturers have used combinations of balancers and suspensions to isolate the basket from the rest of the machine. These devices have provided varying degrees of success in solving the washing machine balance problems.
Known balancers for balancing a rotating body include one or more annular grooves or races and a plurality of balls or rollers which move along the races to counteract the imbalance forces. The races may contain a fluid for damping the motion of the balls. The problem with these known balancers is that they cannot adjust for both of the underlying conditions which cause imbalanced operation. In particular, upon acceleration of the basket at low speeds, the balls inside the balancer must be free to move and able to react quickly to balance the basket as the machine accelerates to an operating speed without causing excessive startup vibration. At higher speeds, the balancer must be able to "set up," or in other words, the balls should remain relatively immobile, in order to provide balanced operation as the machine passes through the rocking mode and at the steady state above the rocking mode.
Accordingly, it would be desirable to provide a speed dependant design for a balancing device which reacts differently depending on the rotational speed of the rotating object.
It would also be desirable to provide a balancing device which adjusts for both start up vibration and instability caused by an imbalanced load at higher speeds.